No smoking gun found as cause of honeybee decline and die-offs

A joint USDA/EPA report addressing the continuing mass die-offs of honeybees points to a wide range of causes. Those include parasites, disease, genetics, poor nutrition and pesticide exposure.

Last October, experts from around the country gathered to assess the state of the science of honeybee health. The report is “the outcome of that conference,” said Sonny Ramaswamy, director of USDA's National Institute of Food and Agriculture, during a Thursday (May 2) press conference.“In many ways it’s a landmark report … and represents the consensus of the scientific community on the challenges our honeybee populations are facing.”

The challenges are complex and, “as in most things biological, there is no smoking gun. The decline in pollinators we’ve observed in recent years is truly due to a whole host of factors. … It is imperative we take action to address the factors contributing to the decline of honeybees and the continuing impacts that our farmers and honey producers are facing.”

How vital are honeybees to U.S. agriculture? Every year, some $20 billion to $30 billion of agricultural U.S. production is dependent on pollination. Seventy percent of the crops Americans rely on for food are pollinated mainly by honeybees.

“It will take all our stakeholders – the agricultural industry, beekeepers, researchers, the federal government and the public,” said Ramaswamy.

At the USDA, “we’re working to improve pollinator-friendly habitats on federal lands so beekeepers have access to good, nutritional forage for their hives. Millions of federal research dollars are supporting focused research projects related to honeybee health. … The USDA is conducting a national survey to identify honeybee pests, which will guide our research and mitigation recommendations as we go forward. We’re also working with farmers and ranchers to integrate pollinator habitat into their land. Just in the past four years, we’ve incorporated pollinator enhancements in the conservation programs such as Environmental Quality Incentive Program, the Conservation Stewardship Program and the Conservation Reserve Program.”

The good news, said Acting EPA Administrator Bob Perciasepe,“is the report indicates there is a range of research and policy steps we can take to start to address these stressors.

Perciasepe pointed to the importance of education on the issues affecting honeybees but also said, “enforcement is important. Later this month, EPA will issue new enforcement guidance … to enhance investigations of bee kill incidents. We’ll also continue outreach to stakeholders to ensure all are aware of the many ways they can report bee kill incidents to EPA.”

A beekeeper's take

The collective body of research “resulting from an unprecedented effort by the scientific community … indicates that bee declines cannot unambiguously be linked to a single causative factor,” said May Berenbaum, professor at the University of Illinois Urbana-Champaign.“This is despite the fact that media outlets have, on multiple occasions, declared that the mystery has been solved.”

A fourth-generation beekeeper, Zac Browning, said the report “makes it fairly clear that bee decline is complicated but not a mystery. It’s really about colony stress. The report does a good job of breaking the known, major stresses into four categories: pest and pathogens, pesticide exposure, nutrition and genetics…

“Since the 1950s, the average farm size in America has grown from about 200 acres to about 400 acres. Average crop yields have increased two- and three-fold. At the same time, honeybee colonies have decreased from about 5.5 million to 2.4 million, today.”

Browning also pointed out the problems for maintaining healthy colonies when there is a lack of crop diversity. “There is roughly 370 million cultivated acres in the lower 48 states. This year, 96 million of those acres will be planted in corn. Cornfields are of no value to honeybees nutritionally.”

Further, “We’re losing suitable habitat for honeybees at unsustainable rates,” said Browning. “In just the last five years we’ve lost over 10 million acres of conservation land, mostly to commodity farming.

“At the same time, while we may be using less pesticides by weight – and perhaps less acutely toxic products – there are few commodity crop acres that aren’t treated with these products. As there is less diversity in the landscape the potential for exposure is amplified, especially as bees are also concentrated and asked to do more and more in terms of pollinating crops. As that demand continues to rise, the supply of bees is steadily declining.”

Browning said what is needed has become clearer. “We need an abundance of clean, nutritious forage for bees. We need better pesticide practices and policies. We need tools to manage pests and disease. We need genetic stocks that give us advantages and resilient strains to pests and pathogens.”

Pesticide questions

The EPA and USDA officials were confronted by several pointed questions regarding pesticides not being front-and-center in the report. The questions were inevitable considering findings of scientists in Europe, where a two-year ban on neonicotinoids is being considered.

“I don’t believe the report deemphasizes pesticides,” said Jim Jones, Acting Assistant Administrator, EPA Office of Chemical Safety and Pollution Prevention. “It was the advice of the experts that led us to the conclusions we are announcing today: there are a range of factors that impact bee health.”

Jones further defended the report. “There are non-trivial costs to society if we get this wrong. (Pesticides) not only provide meaningful benefits to the farmers who use them but they generate benefits to consumers for affordable food.”

Berenbaum said studies of residues in hives have documented the presence of over 100 pesticides and metabolites. “It’s an incredibly complex situation. Pulling out one pesticide doesn’t remove the others. And they aren’t all the result of agricultural exposure. Some of the pesticides – in fact, the residues most frequently encountered – are pesticides used by beekeepers to control the varroa mite, which is the vector of many of the viral diseases that affect honeybees. It isn’t just a simple matter of removing pesticides.”

Agriculture groups react

Agriculture advocacy groups generally praised the report’s findings.

“This report offers additional confirmation that there are numerous factors influencing the health of honeybees,” said Ray McAllister, senior director of regulatory policy for CropLife America. “CLA supports the work of USDA, EPA and all involved stakeholders who are collaborating on developing solutions for honeybees and other pollinators, which are so vital to agricultural production in the U.S. and worldwide. The crop protection industry is dedicated to analyzing the impacts of pesticides on honeybee colonies through continued research into field-relevant pesticide exposures, improvement of pollinator habitats, supporting educational outreach programs and applying best management practices.”

The report “concludes what farmers and scientists have known for some time -- that there isn’t just one cause to the decline in honeybee numbers,” said Bob Stallman, president of the American Farm Bureau Federation. “It’s a multitude of factors, which makes it even more important that we continue work on a solution through collaborative efforts among farmers, beekeepers, researchers, the federal government and the public.

“The good health of the honeybee is extremely important to American agriculture. Many farmers and ranchers require honey bees and other pollinators to produce a healthy, bountiful crop. Farm Bureau supports funding for research to find real answers to the Colony Collapse Disorder, as well as practical, effective methods to remedy the situation.”

The National Cotton Council also weighed in. “Although cotton is a self-pollinating crop that does not require bees for pollination, some beekeepers do request permission to place their hives on cotton producer's property next to row crops, including cotton.

“The NCC has been and continues to be engaged in issues surrounding bee health, and it continues to seek improved crop production techniques that protect crop yield and enhance environmental outcome.”